Greenhouse Gas And Ammonia Emissions And Nutrient Losses From Dairy Manure Composting

Dairy manure composting technology has become an important way of resourceful manure treatment,since it not only can reduce pollution caused by improper disposal from intensive dairy production but also produce a stable,humus-rich,high-quality organic fertilizer.However,the large amount of carbon and nitrogen losses during the composting process not only reduces the agricultural value of compost products as organic fertilizers,but also results in greenhouse gases and ammonia?NH₃?emissions.Aiming at the key issues such as the unclear laws of gases emissions and nutrient losses and unknown factors influencing gases losses during dairy manure composting,a combination of Meta-analysis and in-situ monitoring experiment is used to study the greenhouse gases and ammonia?NH₃?emissions from four main dairy manure compost processes?static,turning,windrow and silo?.Based on 41published literatures?153 cases?and 36-day monitoring data from turning and windrow composting dairy farms,the Meta-analysis results and in-situ experimental conclusions are compared to summarize the laws of greenhouse gases and ammonia?NH₃?emissions and nutrient losses in dairy manure composting and relevant factors which influence gases losses,the main results are as follows:?1?Turning composting would cause the higher greenhouse gases emissions compared to other composting methods,with 6.08 g[CH₄-C]?kg^-1[DM],114.68 g[CO₂-C]?kg^-1[DM]and 4.48 g[N₂O-N]?kg^-1[TN];Silo composts can reduce 82.84%of greenhouse gases emissions than truning composting though they significantly promoted N losses through NH₃ emission;Further researches proved that compared with windrows composting,turning composts can increase CH₄,CO₂,N₂O and NH₃ emissions with 13.43%,23.04%,89.18%and 43.58%,respectively.?2?In the static composting,reducing the initial TC and TN content of composting manure was a more effective way to minimise gaseous losses than adjusting the environmental conditions of composting;The impact of turning events during the turning composts was greater than the effects of compost physicochemical factors on the emissions of CH₄ and N₂O;Reducing the average temperature,initial moisture and initial pH value of the pile can significantly reduce the emissions of CH₄,CO₂ and NH₃ during the windrow composting.?3?On the comprehensive perspective of carbon and nitrogen losses,turning compost was the most detrimental method to preserve nutrients comparing with other composting methods.More than 90%of carbon losses mainly came from CO₂-C,and more than 90%of nitrogen losses mainly came from NH₃-N in the composting.?4?Six main mitigation practices in the dairy manure composting were identified,including "sawdust or straw additive","microorganism additive","phosphogypsum additive","compressed and covered","vermicomposting" and "compost biofilter".Applying compost biofilters was the most effective way to reduce NH₃ emissions during composting with mitigation efficiency value of-97% AMONg such practices;Adding sawdust or straw could reduce CH₄ and N₂O emissions by 66.3% and 44.0% respectively.